Quick Java question

[rushyrulz]

I don't know if I'm retarded or what but I can't for the life of me pass a 2 dimensional array into a method.

correct me if this is the wrong format:

public class Driver
{
	public static void main(String[] args)
	{
		char[][] hello ={{'x', 'o'}, {'o', 'x'}};
		Prog call = new Prog();
		call.displayArray(hello[][]);
	}
}

public class Prog
{
	public Prog()
	{
		System.out.println("sup?");
	}

	public void displayArray(char[][] hi)
	{
		for(int r=0; r<2; r++)
		{
			System.out.println();
			for(int c=0; c<2; c++)
			{
				System.out.print(hi[r][c]);
			}
		}
	}
}

the error I'm getting says '.class' expected. The method program compiles, the driver does not. Pls help D:

EDIT: google is surprisingly stupid when it comes to this shit.
EDIT2: figured it out, apparently, you don't include the brackets when passing an array?

[Frederic54]

Re: Quick Java question

call.displayArray(hello[][]);

Replace it with call.displayArray(hello); and it should work.

[FissionMailed1]

Re: Quick Java question

Why exactly does removing the brackets work though?

Knowing how arrays are stored is a large part to properly understanding them. In this case, the brackets are not necessary as an argument because the parameter requires a pointer to the array. hello[][] is trying to de-reference a specific offset of the array, but what offset?

[SKG_Scintill]

Re: Quick Java question

With the little knowledge that I have: the instance variable "hello" is of the type char[][], so making it hello[][] would mean it's expecting char[][][][] instead of char[][]

I think that's what's going on?

[FissionMailed1]

Re: Quick Java question

If hello is a 2D array, hello[][] isn't 4D, because the bracket operator isn't used as a type declaration.

Passing hello[][] to a function is invalid Java.

[UserNameGoesHere]

Re: Quick Java question

Actually FissionMailed1, Java doesn't use pointers, at least at the programming level. Internally it uses them, true, but it isn't like C++ where you can go referencing and dereferencing pointers all over the place. It hides this from the programmer much like it also hides memory management via garbage collection--sure, it does it, but you don't explicitly tell it to (although you can give it a hint--which the JVM can ignore).

The reason you don't pass hello[][] is because hello[][] is not the name of the variable. The name of the variable is hello. It has nothing to do with pointers. For example, when passing an integer to a function you don't say callsomefunction(int myinteger); but you do say callsomefunction(myinteger);

Leave out type information in method/function calls.

[FissionMailed1]

Re: Quick Java question

The reason I am referring to them as pointers is because I am bypassing the abstraction that Java uses to make a point regarding why the syntax works the way it does. I know you call functions without regard of the type, but as I said, I am trying to make a point.

[SKG_Scintill]

Re: Quick Java question

I am trying to make a pointer.

Fix'd

[FissionMailed1]

Re: Quick Java question

(clap), didn't see that one coming :P

[Patashu]

Re: Quick Java question

EDIT2: figured it out, apparently, you don't include the brackets when passing an array?

You include the brackets when you need to point out the arrayness - e.g. on declaration, construction and indexing it.
When you're just using it as a name or passing it around - the compiler by this point already knows exactly how array-y it is, how many dimensions, how large and so on, so you don't need to tell it again. It's like how you don't say int x = 1; System.out.println(int x), it already knows it's int and you don't need to redeclare.